The present invention relates generally to automotive vehicle systems, and more particularly, to a method and apparatus for adaptively adjusting seat belt tension during vehicle operation.
Active seat systems experience real-time seat movement due to various automotive vehicle maneuvers. An occupant of an active seat system may be subject to real-time seat belt forces that vary in response to range and type of movement of the occupant in the seat system. The varying seat belt forces can become unpleasant to the occupant.
Traditional seat systems are capable of being translated in a fore and aft direction or in an upward and downward direction relative to a vehicle frame. An active seat system incorporates additional mobility by incorporating 4-point actuation, such that the seat system is also capable of tilting in multiple directions about a center point. The center point is located at approximately center between 4-actuators, each actuator is located at an outer base corner of the active seat system.
The all-encompassing mobility of the active seat system is used to aid in counteracting imputed forces on an occupant during vehicle maneuvering. For example, as the vehicle is performing a right turn, the active seat system tilts to the right to offset side forces experienced by an occupant of the vehicle. Instead of the occupant leaning into the turn or physically resisting the lateral forces while in the turn, a portion of the lateral forces are distributed into the active seat system. Similar, active seat system movement is experienced during other vehicle maneuvers including accelerations and braking.
An occupant wearing a seat belt is normally fixed within a seat system. The seat belt is rigidly mounted directly to a vehicle frame, or to a seat frame, which in turn is rigidly mounted to the vehicle frame. The movements of the active seat system during vehicle maneuvering can cause belt pressure on the occupant, which may be discomforting. As the seat system tilts and presses an occupant against the seat belt, any slack in the seat belt decreases and tension of the seat belt increases. The increase in seat belt tension causes the undesirable discomfort experienced by the occupant.
The increase in seat belt tension typically occurs and is most prevalent when the active seat system moves in a forward or upward direction, thereby pressing the occupant tighter against the seat belt.
Multiple energy management systems and vehicle collision systems have been introduced in the past for absorbing energy during a collision, whereby seat belt tension is adjusted during a collision event. These prior systems use collision sensors, which are utilized in determining probability of a collision. In response to the probability of the collision and other vehicle parameters and occupant characteristics, a seat belt pretensioner is activated and seat belt tension is adjusted accordingly. Many pretensioning devices are one-time use devices in that they are triggered during or immediately proceeding a collision and are not reusable. The past systems are incapable of counteracting varying seat belt tensions experienced during normal operating conditions, which do not involve collision prediction and injury prevention.
It would therefore be desirable to develop a technique for adjusting seat belt tension during vehicle maneuvers as to prevent undesirable pressure or discomfort on a vehicle occupant.
The present invention provides a method and apparatus for adaptively adjusting seat belt tension during vehicle operation. An adaptive seat belt system for an automotive vehicle is provided. The system includes a seat belt extensible about an occupant of a seat system. A seat belt tension sensor is coupled to the seat belt and generates a seat belt tension signal. A seat belt actuator is mechanically coupled to the seat belt and adjusts tension of the seat belt. A controller is electrically coupled to the seat belt tension sensor and the seat belt actuator. The controller generates a seat belt tension adjustment signal in response to the seat belt tension signal and adjusts tension of the seat belt in response to the seat belt tension adjustment signal. A method for performing the same is also provided.
One of several advantages of the present invention is the ability to adjust seat belt tension, during vehicle operation, to compensate for seat system movement. The ability to adjust seat belt tension decreases the potential for seat belt discomfort due to seat system movement, especially for active seat systems.
Another advantage of the present invention is that in adjusting seat belt tension, vehicle dynamics, occupant characteristics, and seat system position are considered, thereby, providing seat belt tension determination system for various operating conditions and occupant characteristics. Thus, the system can potentially provide increased occupant safety by maintaining adequate seat belt tension on a vehicle occupant.
Furthermore, the present invention unlike traditional seat belt systems that utilize single use pretensioning devices, the present invention provides active seat belt tension adjustment that is capable of increasing or decreasing seat belt tension continuously during various vehicle operating conditions.
The present invention itself, together with attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying figures.